Installing GNU/Debian Sid in Ubuntu Hardy using debootstrap and chroot

This article explains how to install GNU/Debian Sid in a previously installed Ubuntu Hardy System. We will use debootstrap and chroot tools to accomplish that. This how-to is not focused on security, it does not tell how to create a restricted chroot environment to improve security.

Ubuntu is a GNU/Debian based distro. Every six months they take GNU/Debian Unstable packages and make a new Ubuntu distribution.
Debian Sid provides more and newer packages. Ubuntu is configured for easiness. Debian has less preconfiguration instead.

chroot runs a command with a special root directory.
chroot comes as part of coreutils package.
$ sudo aptitude install coreutils

debootstrap command bootstraps a basic Debian system (it can also bootstrap other systems).
$ sudo aptitude install debootstrap

$ ls /usr/share/debootstrap/scripts/ #shows which distros and versions you can install with debootstrap:

breezy  edgy  etch-m68k  gutsy  hoary  lenny  sarge  sarge.fakechroot  warty  woody 
dapper  etch  feisty  hardy  hoary.buildd  potato  sarge.buildd  sid warty.buildd  woody.buildd

INSTALLATION BEGINNING

First of all we create the directory where Debian Sid will be installed.
$ mkdir DebianSid


CREATING A LOOPBACK IMAGE TO STORE DEBIAN SID

This step is only necessary if you plan to boot your system from your Debian Sid chroot environment.

$ sudo dd if=/dev/zero of=DebianSidFile bs=1048576 count=10000 #We create DebianSidFile with 10 gigabyte capacity.

$ sudo mkfs.ext3 -b 4096 -L DSid DebianSidFile #Ext3 filesystem creation.

$ sudo mount DebianSidFile DebianSid -t ext3 -o loop #mounting it on DebianSid directory.


INSTALLING A MINIMAL SYSTEM

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Joining two AVI files with MENCODER

It is usual having an avi film split into two cdrom sized files of 700 megabytes each.

mencoder utility allows us to concatenate these two parts into a new reintegrate file.

mencoder (MPlayer's Movie Encoder) is a tool MPlayer provides to encode multimedia contents into files.
It supports among others, MPEG-4 video, libavcodec codecs, and PCM/MP3/VBRMP3 audio formats.
mencoder also possesses stream copying abilities and a powerful filter system (crop, expand, flip, ....).


So we have a film split into two files e.g: foo1.avi and foo2.avi, both with the same encoding characteristics (window size, codecs, bitrate...),

We execute this command that produces an output file called foo.avi which is the result of concatenating foo1.avi and foo2.avi files.
$mencoder -oac copy -ovc copy -forceidx foo1.avi foo2.avi -o foo.avi

The command options mean:
* -oac output audio codec
* -ovc output video codec
* -o output file name
* -forceidx forces creation of a new index.
copy means copying the original stream and do not change the codec it is encoded into (because of that it is very fast).


more info executing: $man mencoder

INSTALLING MENCODER

• Ubuntu and Debian: $sudo aptitude install mencoder
• Compiling, Configuring and Installing MPlayer on a Ubuntu (Linux based) System.

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Convert videos to VP6 codec format using MENCODER

Downloading, Compiling and Installing MPlayer on a Ubuntu System

We are going to download MPlayer sources and binary codecs, configure, compile and install them on our Ubuntu system.

I do not want a graphical interface, so I will compile MPlayer without it.

DOWNLOADING MPLAYER SOURCES

We first download the sources: (I pick up the latest source version, if it does not work pick up latest stable one)

(I choose to download it from a German mirror: MPlayer source download page)
$wget http://www7.mplayerhq.hu/MPlayer/releases/mplayer-export-snapshot.tar.bz2

DOWNLOADING BINARY CODECS

MPlayer binary codecs download page

As I have a Linux x86 platform ,I choose its corresponding package:
$wget http://www7.mplayerhq.hu/MPlayer/releases/codecs/essential-20071007.tar.bz2

This page shows an updated list of supported codecs: Codec Status page


In order to install the binary codecs

We create the directory where we will place the codecs:
$sudo mkdir /usr/local/lib/codecs

We untar the codecs and then move them into their place:
$tar xvfj essential-20071007.tar.bz2
$cd essential-20071007/
$sudo cp * /usr/local/lib/codecs

CONFIGURING OSD FONTS

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Connecting to Internet using a Sony Ericsson K530i mobile phone in Ubuntu (Linux) via USB cable

We are going to connect our Ubuntu system to Internet using a Sony Ericsson K530i phone via a usb cable.

First of all we switch on our phone, we insert the pin number and then connect the usb cable that came with the phone to our K530i and to our computer.

A menu presenting three choices will appear on the phone screen:

• File transfer
• Phone mode
• Print

We select Phone mode.

Now our phone is ready to use the usb cable.


There are two ways to connect to Internet via USB:

• Emulating a ethernet device through a usb cable.
• Using the K530i mobile phone as a usb serial modem.

EMULATING A ETHERNET DEVICE THROUGH USB CABLE

Our system Linux kernel has to already be compiled with cdc_ether module support. This module performs the emulation.


Let's configure our phone, we go to:
Menu->Settings->Connectivity->USB->USB Internet->USB data accounts
and select our Internet ISP provider account.

If there is not an already configured account we shall create a new account:
Menu->Settings->Connectivity->Data comm.->Data accounts->New account

Some APNs from Spanish Internet providers are:

Movistar: movistar.es
Vodafone: ac.vodafone.es
Yoigo: internet
Orange: internet

Usually user and password are not needed.


At the end, we establish the connection:
Menu->Settings->Connectivity->USB->USB Internet->Turn on

To check what has happened, we open a console and execute:
$ifconfig

An interface like usb0 with its IP address correctly configured will appear.


When we finish navigating, we switch off the connection:
Menu->Settings->Connectivity->USB->USB Internet->Turn off

USING THE K530i MOBILE PHONE AS A USB SERIAL MODEM

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Hello World program examples

Hello World is the first program every user usually codes when he learns a new programming language.

Its goal is learning the basics to edit, compile and execute a program which sends a "hello world" string to standard output.


We have used an Ubuntu Hardy distro based system. Most commands will serve to other distros as well, like Debian.

BASH Shell Scripting Hello World

bash command line interpreter is usually already installed in your system.

if it is not installed we type: $sudo aptitude install bash


Now we create hello.sh script using whatever text editor we prefer.
e.g: $ gedit hello.sh


Copy this lines into your hello.sh script

#!/bin/bash
echo "hello world"

Bash shell scripting is an interpreted language so we have not to compile anything. We directly execute the shell script file:

We give the shell script execution permissions:
$ chmod a+x hello.sh

and launch the program
$ ./hello.sh

PYTHON Scripting Hello World

If you do not have python installed in your system, exec:

$ sudo aptitude install python

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Emacs Quick Introduction

Installing emacs in a Ubuntu or Debian distro
$sudo aptitude install emacs

Launching emacs
$emacs

If you want to launch emacs in a console without X support, simply exec:
$emacs -nw

Notation:
C-x means mantain pressed control key and then press x key.

Reseting input buffer
C-g resets command input buffer. It is great if you mistyped a command.

Displacement commands:
C-n goes to next line
C-p goes to previous line
C-f goes to next character
C-b goes to previous character
C-a goes to the begining of the line
C-e goes to the end of the line

Deleting, cutting and pasting text
C-d deletes character under the cursor
C-k cuts from the cursor position until the end of the line.
C-y pastes previous cut text.

Undo command
C-x u undoes previous command.

Dealing with files
C-x C-f opens a file
C-x C-w saves current file.

Closing emacs
C-x C-c closes emacs.

Passing arguments to commands:
E.g: C-u 8 C-n Advances eight lines.

Reading emacs self-documentation:
C-h t opens emacs tutorial


These are the minimal set of commands to work with emacs like a notepad.

Emacs is an extremely powerful and flexible text editor. You are not even on the surface of emacs potential. I recommend you to study and use it.

Backing and Restoring Mediawiki in Ubuntu

We are going to learn how to back up and restore our Mediawiki installed on a Ubuntu system.

To acomplish that we will execute some wiki maintenance commands.
These maintenance commands will be accesible after configuring AdminSettings.php file.

CONFIGURING AdminSettings.php FILE

AdminSettings.sample from the Mediawiki examples documentation will serve us as a model file to start.

We copy it into mediawiki configuration directory in /etc and assign the correct owner and permissions.
$sudo cp /usr/share/doc/mediawiki1.10/examples/AdminSettings.sample /etc/mediawiki1.10/AdminSettings.php
$sudo chown root:root /etc/mediawiki1.10/AdminSettings.php
$sudo chmod 600 /etc/mediawiki1.10/AdminSettings.php


Now we are going to edit AdminSettings.php file
$gksudo gedit /etc/mediawiki1.10/AdminSettings.php

Change these two variables using the parameters you used when creating the wiki database: e.g: wikiuser and its password.
$wgDBadminuser = 'DB user name'
$wgDBadminpassword = 'DB password'

Now that AdminSettings.php file is properly configured we are gonna back up and restore the wiki.

BACKING UP THE WIKI

dumpBackup.php command will back up our wiki:
$cd /var/lib/mediawiki1.10/maintenance
$sudo php dumpBackup.php --current > ~/foo_backup.xml
NOTE: --full option backups history of pages, not only last version as --current does.

RESTORING THE WIKI

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Installing and Configuring Mediawiki on a Ubuntu Gutsy Desktop System

Mediawiki is the web based tool (wiki software) that Wikipedia uses to manage, store and serve its contents.

Mediawiki is written in PHP, and in this installation we will use MySQL as database management system (although it can be configured to use PostgreSQL)

Mediawiki is ditributed under the GNU GPL license.

INSTALLING MEDIAWIKI

First step is installing MySQL:
$sudo aptitude install mysql-admin mysql-server

It will ask you for MySQL root password. Then choose a secure password and type it.


Now we install Mediawiki itself:
$sudo aptitude install mediawiki

It will automatically check for apache and php dependencies.

Current mediawiki version is 1.10.


At installation I get this warning:
apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1 for ServerName

There is some info in this thread at ubuntu forums.

To get rid of the error:
$gksudo gedit /etc/apache2/httpd.conf

httpd.conf file is usually empty, and then we add this line:
ServerName localhost

After saving the file we check if the error is gone executing this command:
$sudo apache2ctl restart

SETTING MEDIAWIKI URL ALIAS

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GNU/Linux SYSTEM DIRECTORIES and their FILESYSTEMS

Executing $ ls / lists the top level of the root filesystem tree. There appear directories like:
/dev, /etc, /proc, /sys, /var, /tmp and others.

In this article we are going to deal with directories that have special filesystems associated with them.


For a general view of the filesystem hierarchy we can visit the Filesystem Hierarchy Standard page.

FHS standard is a set of guidelines about where to place files and directories within UNIX based operating systems.

Check which filesystems are mounted

Two commands allow us to examine which filesystems and where are currently mounted in our system.

$ mount
or
$ cat /etc/mtab


Their response will be something like that:

/dev/sda1 on / type ext3 (rw,errors=remount-ro)
proc on /proc type proc (rw,noexec,nosuid,nodev)
/sys on /sys type sysfs (rw,noexec,nosuid,nodev)
varrun on /var/run type tmpfs (rw,noexec,nosuid,nodev,mode=0755)
varlock on /var/lock type tmpfs (rw,noexec,nosuid,nodev,mode=1777)
udev on /dev type tmpfs (rw,mode=0755)
devshm on /dev/shm type tmpfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
lrm on /lib/modules/2.6.22-14-generic/volatile type tmpfs (rw)
securityfs on /sys/kernel/security type securityfs (rw)

We are specially interested in /proc, /sys, /var/run, /var/lock, /dev, /dev/shm, /dev/pts, /sys/kernel/security

/proc directory

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Reverse Engineering Python Code with PyNSource

PyNSource is a tool that allow us to obtain UML diagrams from python source code.

PyNSource Web Page


INSTALLING PyNSource ON AN UBUNTU GUTSY SYSTEM.

NOTE: You must have python already installed in your system. I assume 2.5 version.

$mkdir PyNSource
$cd PyNSource


Now we download the program and install it:
$wget http://www.atug.com/downloads/pynsource1.4c.zip
$unzip pynsource1.4c.zip
$sudo python setup.py install


We want to run the GUI so we need a graphical library:
$sudo aptitude install python2.5-wxgtk2.6

Current code does not work with version wxgtk2.6 so we need to update it:
$wget http://www.atug.com/andypatterns/code/pyNsourceGui1.4c-wx26.zip
$unzip pyNsourceGui1.4c-wx26.zip
$sudo cp pyNsourceGui-wx26.py /usr/lib/python2.5/site-packages/pynsource/


Finally we exec the GUI module
$python /usr/lib/python2.5/site-packages/pynsource/pyNsourceGui-wx26.py


This application presents some annoying bugs:

* There are problems when moving shapes on the screen. It does not refresh correctly.
* It is difficult to adjust page size when you try to print it.
* When you press right click button on the mouse to delete an object, usually it doesn't delete all the arrows that point to it, messing the schema.
* Saving and opening diagram feature is not implemented yet, so you cannot save temporary work.


Well, you know, this bugs are annoying, but it you dont like them, it is free software, so hack the code. :-)